Lysis of intraventricular blood clot with urokinase in a canine model: Part 1. Canine intraventricular blood cast model.

To test the safety and feasibility of using direct instillation of urokinase to induce rapid lysis of intraventricular clots, an animal model of intraventricular blood cast is required. Injections of 11 ml of fresh, unclotted autologous blood into the ventricles of adult mongrel dogs did not produce a solid blood cast in the ventricular system, suggesting that the adult dogs have an unusual ability to clear uncoagulated whole blood from the ventricles and subarachnoid space. Injection of 9 ml of preclotted blood resulted in a subtotal cast of the ventricles, leaving only portions of the occipital horns free of solid clots. This volume of injected clots incurred no mortality and minimal morbidity, whereas injection of 10 to 12 ml resulted in a mortality of 42% and formidable morbidity. The technique of producing this intraventricular blood cast model, as well as that of implanting an indwelling ventricular catheter-reservoir system useful in chronic urokinase administration, is described.